/*
 * Copyright 2005-2010 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.wamblee.test.inject;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.wamblee.inject.Injector;
import org.wamblee.reflection.Accessor;
import org.wamblee.reflection.AnnotationUtils;
import org.wamblee.reflection.ObjectTraversal;
import org.wamblee.reflection.ObjectTraversal.ObjectVisitor;

/**
 * <p>
 * Injector that performs additional injection on top of the injections that are
 * standard available (e.g. entity manager in Java SE environment).
 * </p>
 * 
 * <p>
 * It works by first delegating to the default injector (typically CDI).
 * Afterwards it traverses the object graph of the injected object and performs
 * custom injection of test objects as specified by the {@link Binding} class.
 * This approach makes sure that test dependencies also find their way into
 * objects that were created by the injection framework.
 * </p>
 * 
 * @author Erik Brakkee
 */
public class JavaEETestInjector implements Injector {

    private class InjectionVisitor implements ObjectVisitor {
        @Override
        public boolean mustVisit(Class aClass) {
            if (EntityManager.class.isAssignableFrom(aClass)) {
                return false;
            }
            return true;
        }

        @Override
        public boolean mustVisit(Field aField) {
            // just process any field with annotations
            return aField.getAnnotations().length > 0;
        }

        @Override
        public boolean mustVisit(Method aMethod) {
            return false;
        }

        @Override
        public boolean visitArray(Object aArray) {
            return true;
        }

        @Override
        public boolean visitList(List aObject) {
            return true;
        }

        @Override
        public boolean visitMap(Map aObject) {
            return true;
        }

        @Override
        public boolean visitPlainObject(Object aObject) {
            performTestInjections(aObject);
            return true;
        }

        @Override
        public boolean visitSet(Set aSet) {
            return true;
        }
    }

    private List<Binding> bindings;
    private Injector delegate;

    /**
     * Constructs the injector.
     * 
     * @param aClass
     *            Class to inject for.
     * @param aBindings
     *            Binding of an object value.
     * @param aDelegate
     *            Injecto to delegate to to perform the standard injections.
     */
    public JavaEETestInjector(Class aClass, List<Binding> aBindings,
        Injector aDelegate) {
        bindings = aBindings;
        delegate = aDelegate;
    }

    @Override
    public void inject(Object aComponent) {
        // basic injection
        delegate.inject(aComponent);

        // Now perform test injections.
        ObjectTraversal traversal = new ObjectTraversal(new InjectionVisitor());
        traversal.accept(aComponent);
    }

    private void performTestInjections(Object aComponent) {
        for (Binding binding : bindings) {
            binding.inject(aComponent);
        }
    }

}